Dr. Yenming Huang Invited talk at 2019 Future Tech Exhibition, Taipei, Taiwan

1. 5G Low Latency Massive Access Technology
(5G低延遲大規模通訊技術)
Speaker: Dr. Yenming Huang 黃彥銘
Main Project Participants:
• Director Prof. Hsuan-Jung Su 蘇炫榮
• Prof. Borching Su 蘇柏青
• Prof. Tzi-Dar Chiueh 闕志達
Affiliation: National Taiwan University
Date: December 8, 2019
This project has received funding from the European Union's Horizon 2020
research and innovation programme under grant agreement No 761745,
and the Ministry of Science and Technology, Taiwan.
Contact emails: hjs@ntu.edu.tw; d01942015@ntu.edu.tw

2. 5G and the Factories of the Future (FoF)
5G New Radio (NR) highlights three major service categories operated in a broad range of
frequencies and deployment scenarios:
• enhanced mobile broadband (eMBB),
• ultra-reliable low-latency communications (URLLC),
• massive machine type communications (mMTC).
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Factories of the Future (FoF), namely, Industry 4.0,
is envisioned to be one of the most important 5G
applications mainly related to URLLC and mMTC.
Figure sources:
[1] ITU on Twitter available at https://twitter.com/itu/status/1039885559399936000
[2] White paper: 5G and the Factories of the Future, available at https://5g-ppp.eu/wp-content/uploads/2014/02/5G-PPP-White-Paper-on-Factories-of-the-Future-Vertical-Sector.pdf

3. Industry 4.0 Service Related Value Creation
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[1] https://trunovate.com/blog/what-is-industry-4-0-and-why-its-important/
[2] https://www.forbes.com/sites/bernardmarr/2018/09/02/what-is-industry-4-0-heres-a-super-easy-explanation-for-anyone/#345b071a9788
[3] White paper: 5G and the Factories of the Future, available at https://5g-ppp.eu/wp-content/uploads/2014/02/5G-PPP-White-Paper-on-Factories-of-the-Future-Vertical-Sector.pdf

4. PHY Signal Requirements of 5G and the FoF (1/3)
To enable 5G low latency massive access technology such as FoF, there are physical-layer
(PHY) signal requirements to be met.
• Demand 1: Mission-critical message exchange
The signal length per transmission shall be as short as possible to reduce latency.
The signal format shall be highly flexible and scalable to adapt to practical environments to warrant
high reliability.
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CP N-point IFFT output
N-point IFFT output
Latency
reduction
5G FoF OFDM-based block
4G OFDM block
Ref: S.-Y. Lien et al., “5G New Radio: waveform, frame structure, multiple access, and initial access,” IEEE Communications Magazine, June 2017.
Figure source: Y. Huang, “Circularly pulse-shaped precoding for OFDM: a new waveform and its transceiver optimization design,” Ph.D. dissertation, National Taiwan University, Taiwan, 2019.
Abbreviations: Cyclic prefix (CP); Inverse fast Fourier transform (IFFT)

5. PHY Signal Requirements of 5G and the FoF (2/3)
To enable 5G low latency massive access technology such as FoF, there are physical-layer
(PHY) signal requirements to be met.
• Demand 2: Massive connectivity
The waveform transmissions possess low out-of-subband emission (OSBE) to provide more users
coexisting in a frequency band.
Non-orthogonal multiple access (NOMA) schemes enable more than one user served in the same
time-frequency resources to increase spectral efficiency (SE).
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Ref: Y. Huang, R. Yang, and B. Su, “Integrating sparse code multiple access with circularly pulse-shaped OFDM waveform for 5G and the factories of the future,” in Proc. EuCNC, June 2019.
Figure source: Y. Huang, “Circularly pulse-shaped precoding for OFDM: a new waveform and its transceiver optimization design,” Ph.D. dissertation, National Taiwan University, Taiwan, 2019.
Multiple users
superimposed
in the same subband

6. PHY Signal Requirements of 5G and the FoF (3/3)
To enable 5G low latency massive access technology such as FoF, there are physical-layer
(PHY) signal requirements to be met.
• Demand 3: Low-cost devices and machines
The transmitted signal with low peak-to-average power ratio (PAPR) is practically needed to enhance
power amplifier (PA) efficiency.
Good PA efficiency may
 prevent undesirable spectral regrowth,
 alleviate signal nonlinear distortion,
 save battery life.
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Ref: Y. Huang, R. Yang, and B. Su, “Reducing cubic metric of circularly pulse-shaped OFDM signals through constellation shaping optimization with performance constraints,” in Proc. VTC, Aug. 2018.
Figure source: Y. Huang, “Circularly pulse-shaped precoding for OFDM: a new waveform and its transceiver optimization design,” Ph.D. dissertation, National Taiwan University, Taiwan, 2019.
Abbreviation: Digital-to-analog converter (DAC)
Transmitter DAC
Data bits
PA
Wireless
channel

7. NOMA and OFDM-based Waveform Designs
• New non-orthogonal multiple access (NOMA) and orthogonal frequency division multiplexing (OFDM)
based waveform designs are critical to meet the physical-layer (PHY) requirements of 5G low latency
massive access technology.
• Block diagram of baseband NOMA-OFDM-based transmitter:
7Figure source: Y. Huang, “Circularly pulse-shaped precoding for OFDM: a new waveform and its transceiver optimization design,” Ph.D. dissertation, National Taiwan University, Taiwan, 2019.
WOLA-OFDM (by Qualcomm)
UF-OFDM (by Nokia) with ZP and f-OFDM (by Huawei)
DFT-S-OFDM (a.k.a. SC-FDMA) and SS-SC-FDMA (by NTT Docomo)
ZT DFT-S-OFDM (by Nokia) and CPS-OFDM (by NTU)
0100110001 …

8. Integrating SCMA With CPS-OFDM
• Circularly pulse-shaped OFDM (CPS-OFDM) is one of the
most promising 5G waveforms that
• possesses the advantages of both low OSBE and low PAPR,
• characterizes DFT-based subband precoder flexibility, and so
- prevents block extension increasing latency,
- supports no guard interval due to smooth block transition,
- be efficiently implemented with linearithmic-order complexity,
- provides backward and forward compatibility,
• offers more satisfactory detection reliability and spectral efficiency,
as compared to other multicarrier waveform candidates such as
OFDMA, WOLA-OFDM, f-OFDM, and UF-OFDM.
• Sparse code multiple access (SCMA) has attracted much
attention in recent years that
• is a multi-dimensional codebook-based NOMA technique,
• benefits from codeword sparsity substantially decreasing multiuser
detection complexity at the receiver,
• provides constellation shaping gain enhancing detection reliability.
• can be realized with different codebooks in manifold PHY aspects.
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Figure sources and references:
[1] Y. Huang, R. Yang, and B. Su, “Integrating sparse code multiple access with circularly pulse-shaped OFDM waveform for 5G and the factories of the future,” in Proc. EuCNC, June 2019.
[2] Deliverable 2.3 PHY Solutions in Clear5G project.

9. Advantages of Proposed SCMA-CPS-OFDM
• SCMA-CPS-OFDM leads to the lowest amount of OSBE in adjacent bands mainly due to the CPS precoder
design addressing PAPR reduction at the same time to prevent spectral regrowth.
• SCMA-CPS-OFDM yields the lowest PAPR as compared to the others, since its design degrees of freedom
can be optimized for limiting the envelope fluctuation according to the statistics of the encoded symbols.
• SCMA-CPS-OFDM system can offer the most satisfactory detection reliability and spectral efficiency.
• Notice that CPS-OFDM possesses the shortest transmission block processing latency, compared to the
other waveforms, much friendly to 5G low latency massive access technology.
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Figure sources:
[1] Y. Huang, R. Yang, and B. Su, “Integrating sparse code multiple access with circularly pulse-shaped OFDM waveform for 5G and the factories of the future,” in Proc. EuCNC, June 2019.
[2] Deliverable 2.3 PHY Solutions in Clear5G project.

10. Concluding Remarks and Future Plans
• SCMA-CPS-OFDM is proposed to enable 5G low latency massive access technology, e.g., 5G and the FoF,
more specifically, this PHY solution is to support
• mission-critical message exchange (requiring low latency, high reliability, and high flexibility),
• massive connectivity (requiring low spectral leakage and high spectral efficiency),
• low-cost devices and machines (requiring high power amplifier efficiency).
• Next step is to integrate SCMA-CPS-OFDM into 5G massive MIMO systems to enhance spectral efficiency.
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Figure sources:
[1] Klaus Moessner, “Clear5G Communication for the Factories of the Future,” PPT report slides, in Proc. EuCNC Workshop 6 : European and Taiwanese Cooperation on 5G, June 2019.
[2] White paper: Factories of the Future, available at https://www.effra.eu/sites/default/files/factories_of_the_future_2020_roadmap.pdf
Traditional factory 5G smart factory